Claim CB030.1:
Since the early atmosphere had no ozone layer, ultraviolet (UV) light
would have irradiated organic molecules that formed in the atmosphere,
destroying complex molecules.
Source:
Watchtower Bible and Tract Society. 1985. Life--How Did It Get Here?
Brooklyn, NY, p. 41.
Response:
- When simple organic molecules are held together in a fairly
concentrated area, such as stuck to a dust or ice grain, the UV light
actually enhances the formation of more complex molecules by breaking
some bonds and allowing the molecules to recombine (Bernstein et al.
1999; Cooper et al. 2001). DNA and RNA are relatively resistant to UV
light, because some parts of the molecules shelter others and damage
to the bases can provide the materials to repair the backbone. UV
light gives nucleic acids a selective advantage and may in fact have
been an essential ingredient for abiogenesis (Mulkidjanian et al. 2003;
Mullen 2003).
- The molecules need not all have stayed exposed to UV for long. Some
would have dissolved in oceans and lakes. In one proposed scenario,
the complex organic molecules form in the deep ocean around geothermal
vents, well away from ultraviolet light.
References:
- Bernstein, M. P., S. A. Sandford, L. J. Allamandola, J. S.
Gillette, S. J. Clemett and R. N. Zare. 1999. UV irradiation of
polycyclic aromatic hydrocarbons in ices: Production of alcohols,
quinones, and ethers. Science 283: 1135-1138. See also:
Ehrenfreund, P., 1999. Molecules on a space odyssey. Science 283:
1123-1124.
- Cooper, G. et al. 2001. Carbonaceous meteorites as a source of
sugar-related organic compounds for the early Earth. Nature 414:
879-883. See also: Sephton, M. A., 2001. Life's sweet beginnings?
Nature 414: 857-858.
- Mulkidjanian, A. Y., D. A. Cherepanov and M. Y. Galperin. 2003.
Survival of the fittest before the beginning of life:
selection of the first oligonucleotide-like polymers by UV light.
BMC Evolutionary Biology 3:12.
http://www.biomedcentral.com/1471-2148/3/12/abstract
- Mullen, Leslie. 2003. Shining light on life's origin. Astrobiology
Magazine, http://www.astrobio.net/news/article492.html
Further Reading:
Bernstein, M. P., S. A. Sandford and L. J. Allamandola. 1999. Life's
far-flung raw materials. Scientific American 281(1) (July): 42-49.
created 2001-2-17, modified 2004-6-12